On the Detection Potential of Blazar Flares for Current Neutrino Telescopes

TL;DR

This paper assesses the potential for current neutrino telescopes like IceCube to detect neutrinos from blazar flares, finding that most individual flares are unlikely to produce detectable signals, but highlighting specific blazars as promising sources.

Contribution

It provides a quantitative analysis of neutrino detection prospects from blazar flares, identifying key sources and proposing strategies for future searches.

Findings

Most blazar flares have too small fluence for neutrino detection.

The neutrino detection probability from individual flares is generally low.

Blazars 3C 279 and PKS 1510-089 are the most promising sources.

Abstract

Blazar jets are extreme environments, in which relativistic proton interactions with an ultraviolet photon field could give rise to photopion production. High-confidence associations of individual high-energy neutrinos with blazar flares could be achieved via spatially and temporally coincident detections. In 2017, the track-like, extremely high-energy neutrino event IC 170922A was found to coincide with increased $\gamma$-ray emission from the blazar TXS 0506+056, leading to the identification of the most promising neutrino point source candidate so far. We calculate the expected number of neutrino events that can be detected with IceCube, based on a broadband parametrization of bright short-term blazar flares that were observed in the first 6.5 years of \textit{Fermi}/LAT observations. We find that the integrated keV-to-GeV fluence of most individual blazar flares is far too small to yield a substantial Poisson probability for the detection of one or more neutrinos with IceCube. We show that the sample of potentially detectable high-energy neutrinos from individual blazar flares is rather small. We further show that the blazars 3C 279 and PKS 1510$-$089 dominate the all-sky neutrino prediction from bright and short-term blazar flares. In the end, we discuss strategies to search for more significant associations in future data unblindings of IceCube and KM3NeT.